Short answers, pulled from the story.
The Battle of Madagascar, also known as Operation Ironclad, took place from May to November 1942. Allied forces launched the invasion on the 5th of May 1942 and concluded hostilities with an armistice signed in Ambalavao on the 6th of November 1942.
Major-General Robert Sturges of the Royal Marines commanded Force 121 which executed the operation. Rear-Admiral Edward Syfret commanded naval Force H while Governor General Armand Léon Annet led the defending Vichy French forces at Diego-Suarez.
Japan sought forward bases in Madagascar to threaten Allied lines of communication across a region stretching from the Pacific and Australia to the Middle East and South Atlantic. The Imperial Japanese Navy planned to use submarines based there to disrupt shipping routes after their conquest of Southeast Asia by February 1942.
Allied forces landed approximately 8,000 troops including three infantry brigades of the 5th Division and No. 5 Commando units. Defending Vichy forces included about 8,000 troops with roughly 6,000 being Malagasy tirailleurs concentrated around the bay.
Japanese midget submarine I-20 fired two torpedoes that seriously damaged the battleship Ramillies on the 30th of May 1942. The ship required extensive repairs in Durban and Plymouth while the crew of the midget submarine Lieutenant Saburo Akieda and Petty Officer Masami Takemoto were killed in a firefight three days later.